Known fire protection systems for road tunnels include fixed firefighting systems that deliver water or other firefighting agent to address a vehicle fire such as, for example, a wheel well fire, a passenger compartment fire, multiple vehicle fires, tractor trailer fires, or fires involving flammable liquid spills or pallets. Water-based fixed firefighting systems can include deluge systems that employ water spray or water mist devices that are always open to deliver the water or water mist at a desired rate or flow (volume per unit of time) and at a desired density or application rate (flow per unit of area). Delivery of water to the sprinklers or nozzles is controlled by one or more fluid control valves, such as for example, deluge valves. The water delivery, control and application can be designed with the objective of protecting occupants in their vehicles, protecting occupants during escape on foot, and managing products of combustion.
The tunnel and the areas to be protected by the fire protection system generally include the roadway, the roof and/or ceiling above the roadway, and the sidewalls which extend from the roof to the roadway. For large tunnels, it can be desirable to divide the area of protection into zones, in which the response and delivery of water to the zones can be individually controlled. The size of the individual zones to be protected is defined by the available water supply and resulting hydraulics, e.g., flow, density and operating pressure requirements of the system and its water distribution devices. The ability of the system to apply water at a designed density within a given zone is a function of the number of devices in the zone, the coverage area of the individual devices, and the spacing and orientation of the devices relative to the protection area and any obstructions or system components within the zone. Generally, the coverage area of the individual device is a function of the geometric area covered by the spray or mist, the operating pressure of the device and its discharge characteristics. Spacing, installation and orientation of the water discharge devices is defined by the piping and fittings interconnecting the devices to one another and the water supply. The number of devices and the amount of piping employed can impact the overall cost of the system. Accordingly, it is desirable to minimize or optimize the number of devices and/or the amount of piping and fittings to meet the design objectives of the system. Although prior system designs hypothesize minimized supply piping, such designs do not detail the coupling arrangements between the device and the supply piping to provide the designed density and protection over a specified zone.